Plant traits of grass and legume species for flood resilience and N 2 O mitigation

peer-reviewed1. Flooding threatens the functioning of managed grasslands by decreasing primary productivity and increasing nitrogen losses, notably as the potent greenhouse gas nitrous oxide (N2O). Sowing species with traits that promote flood resilience and mitigate flood-induced N2O emissions within these grasslands could safeguard their productivity while mitigating nitrogen losses. 2. We tested how plant traits and resource acquisition strategies could predict flood resilience and N2O emissions of 12 common grassland species (eight grasses and four legumes) grown in field soil in monocultures in a 14-week greenhouse experiment. 3. We found that grasses were more resistant to flooding while legumes recovered better. Resource-conservative grass species had higher resistance while resource-acquisitive grasses species recovered better. Resilient grass and legume species lowered cumulative N2O emissions. Grasses with lower inherent leaf and root δ13C (and legumes with lower root δ13C) lowered cumulative N2O emissions during and after the flood. 4. Our results highlight the differing responses of grasses with contrasting resource acquisition strategies, and of legumes to flooding. Combining grasses and legumes based on their traits and resource acquisition strategies could increase the flood resilience of managed grasslands, and their capability to mitigate flood-induced N2O emissions

Feedbacks of plant identity and diversity on the diversity and community composition of rhizosphere microbiomes from a long-term biodiversity experiment

Soil microbes are known to be key drivers of several essential ecosystem processes such as nutrient cycling, plant productivity and the maintenance of plant species diversity. However, how plant species diversity and identity affect soil microbial diversity and community composition in the rhizosphere is largely unknown. We tested whether, over the course of 11 years, distinct soil bacterial communities developed under plant monocultures and mixtures, and if over this time frame plants with a monoculture or mixture history changed in the bacterial communities they associated with. For eight species, we grew offspring of plants that had been grown for 11 years in the same field monocultures or mixtures (plant history in monoculture vs. mixture) in pots inoculated with microbes extracted from the field monoculture and mixture soils attached to the roots of the host plants (soil legacy). After 5 months of growth in the glasshouse, we collected rhizosphere soil from each plant and used 16S rRNA gene sequencing to determine the community composition and diversity of the bacterial communities. Bacterial community structure in the plant rhizosphere was primarily determined by soil legacy and by plant species identity, but not by plant history. In seven of the eight plant species the number of individual operational taxonomic units with increased abundance was larger when inoculated with microbes from mixture soil. We conclude that plant species richness can affect below-ground community composition and diversity, feeding back to the assemblage of rhizosphere bacterial communities in newly establishing plants via the legacy in soil.</p

Belowground links between root properties of grassland species and N2O concentration across the topsoil profile

Plants can affect N2O emissions by enhancing nitrogen (N) uptake and other below-ground interactions. However, the specific effect of the root systems of different plant species on the production and accumulation of N2O within the soil profile remain largely unknown. The aim of this study was to investigate how plant species from different functional groups, their productivity and root traits affect N2O emissions and N2O concentrations within the soil profile in a fertilised grassland. We conducted a field experiment with two grasses (Phleum pratense, Lolium perenne), two legumes (Trifolium repens, Trifolium pratense), two forbs (Cichorium intybus, Plantago lanceolata), and the six-species mixture in a fertilised grassland. The effects of these plant communities on N-cycling processes were then assessed through the measurement of above- and below-ground plant traits, plant productivity, soil nutrient availability, N2O emissions and its distribution in the soil profile. We found that C. intybus and P. pratense had the lowest N2O emissions from the soil, which was mainly related to higher root biomass. The six-species mixture also showed lower N2O emissions compared to L. perenne monoculture which was explained by complementary effects between the different plant species. We did not find a relationship between N2O emission and its concentration in the soil profile. Higher specific root length and root length density coincided with higher N2O concentrations at 10-20 and 20-30 cm soil depths. Since these two traits have been previously linked to reductions in N2O emissions emitted from the soil, our results show that the relationships between root traits and N2O emissions may not be reflected down in the soil profile. Overall, this study underscores the often-neglected importance of root traits for N-cycling and emphasises the need to better understand how root traits modify N2O consumption within the soil profile to design more sustainable grasslands

A method to evaluate enhanced rock weathering using intact soil monoliths under field conditions

Enhanced rock weathering (ERW) has attracted considerable attention as a carbon dioxide removal (CDR) strategy. However, a reliable method for accurately measuring, monitoring, and verifying carbon dioxide (CO2) removal, particularly under field conditions, remains elusive. Here we describe a method for installing soil monoliths in an in situ buried apparatus that allows collection of water draining through a soil, undisturbed by external environmental factors that may affect similar apparatus located above ground. The method provides a robust, cost-effective means of collecting, developing, and establishing soil monoliths, allowing through drainage soil water sample collection and analysis, and so facilitating estimation of ERW CO2 removal. A 200 mm diameter polyvinyl chloride (PVC) pipe is inserted into the soil to extract intact monoliths from a site of interest, withdrawn and then fitted with a basal double socket coupling and end cap for leachate collection. It is buried to reproduce soil environmental conditions, and water is collected via a sampling tube to surface. Validity was confirmed through an experimental trial with 36 monoliths over 6 months. This method enables accurate chemical analysis of solute draining through the soil monolith, which can be used to validate models of ERW efficacy. •PVC pipes are inserted into the target soil and subsequently extracted to retrieve intact soil monoliths. •PVC sockets, equipped with a mesh and a geotextile membrane in the middle to retain the collected intact soil monolith and prevent soil particle transport, are then attached to the PVC pipe. •PVC caps, featuring a small drainage tube attached to its outer side, are used to collect the leachate at the bottom part of the system

Cover crop identity determines root fungal community and arbuscular mycorrhiza colonization in following main crops

Cover crops (CC) can promote nutrient retention and recycling for main crops yet may also promote soilborne pathogens or suppress beneficial root symbionts such as arbuscular mycorrhizal fungi (AMF). We investigated how root fungal communities of main crop are affected by preceding CC monocultures and mixtures and by main crop identity. We expected that AMF abundance and diversity in main crops are promoted by AM-host CC, and suppressed by non-AM-host CC, and that mixtures of CC species can promote beneficial and suppress pathogenic root fungi. Our full-factorial field experiment comprised crop rotation in sand soil with different CC treatments (monocultures of radish [AM non-host], ryegrass, clover, vetch [AM hosts], mixtures of radish + vetch, ryegrass + clover and fallow) and two main crops (oat and endive). At peak crop growth, we investigated the root fungal communities in the main crops using microscopy and high throughput sequencing (Illumina MiSeq). Cover crop identity was of prime importance and CC legacy overruled main crop identity in determining root fungal communities in main crops. Compared with fallow, CC with ryegrass increased AMF colonization and richness in both main crops and of non-AMF in oat. Legacies of ryegrass, ryegrass + clover and vetch resulted in distinct root fungal communities in the main crops, while the legacy of CC with radish were similar to the legacy of fallow. Root fungal community in crops after clover had highest abundance of representative fungal pathogens in contrast with the other CC treatments that resulted in fungal communities where pathogens were scarce. Oppositely to expected, CC mixtures did not enhance fungal symbionts or suppressed pathogens. Overall, fungal communities in roots of the main crops in our field experiment were determined by the preceding CC species in monoculture, rather than by the CC AMF preference or functional group. This research highlights that the choice of CC determines the root fungal community in main crop which may influence crop quality

Perspectives on the scientific legacy of J. Philip Grime

Perhaps as much as any other scientist in the 20th century, J.P. Grime transformed the study of plant ecology and helped shepherd the field toward international prominence as a nexus of ideas related to global environmental change. Editors at the Journal of Ecology asked a group of senior plant ecologists to comment on Grime's scientific legacy. This commentary piece includes individual responses of 14 scientists from around the world attesting to Grime's foundational role in plant functional ecology, including his knack for sparking controversy, his unique approach to theory formulation involving clever experiments and standardized trait measurements of large numbers of species, and the continued impact of his work on ecological science and policy

Soil-derived Nature’s Contributions to People and their contribution to the UN Sustainable Development Goals

Acknowledgments The input of PS contributes to Soils-R-GRREAT (NE/P019455/1) and the input of PS and SK contributes to the European Union's Horizon 2020 Research and Innovation Programme through project CIRCASA (grant agreement no. 774378). PR acknowledges funding from UK Greenhouse Gas Removal Programme (NE/P01982X/2). GB De Deyn acknowledges FoodShot Global for its support. TKA acknowledges the support of “Towards Integrated Nitrogen Management System (INMS) funded by the Global Environment Facility (GEF), executed through the UK’s Natural Environment Research Council (NERC). The input of DG was supported by the New Zealand Ministry of Business, Innovation and Employment (MBIE) strategic science investment fund (SSIF). PMS acknowledges support from the Australian Research Council (Project FT140100610). PM’s work on ecosystem services is supported by a National Science Foundation grant #1853759, “Understanding the Use of Ecosystem Services Concepts in Environmental Policy”. LGC is funded by National Council for Scientific and Technological Development (CNPq, Brazil – grants 421668/2018-0 and 305157/2018-3) and by Lisboa2020 FCT/EU (project 028360). BS acknowledges support from the Lancaster Environment Centre Project.Peer reviewedPostprin

Enhancement of Late Successional Plants on Ex-Arable Land by Soil Inoculations

Restoration of species-rich grasslands on ex-arable land can help the conservation of biodiversity but faces three big challenges: absence of target plant propagules, high residual soil fertility and restoration of soil communities. Seed additions and top soil removal can solve some of these constraints, but restoring beneficial biotic soil conditions remains a challenge. Here we test the hypotheses that inoculation of soil from late secondary succession grasslands in arable receptor soil enhances performance of late successional plants, especially after top soil removal but pending on the added dose. To test this we grew mixtures of late successional plants in arable top (organic) soil or in underlying mineral soil mixed with donor soil in small or large proportions. Donor soils were collected from different grasslands that had been under restoration for 5 to 41 years, or from semi-natural grassland that has not been used intensively. Donor soil addition, especially when collected from older restoration sites, increased plant community biomass without altering its evenness. In contrast, addition of soil from semi-natural grassland promoted plant community evenness, and hence its diversity, but reduced community biomass. Effects of donor soil additions were stronger in mineral than in organic soil and larger with bigger proportions added. The variation in plant community composition was explained best by the abundances of nematodes, ergosterol concentration and soil pH. We show that in controlled conditions inoculation of soil from secondary succession grassland into ex-arable land can strongly promote target plant species, and that the role of soil biota in promoting target plant species is greatest when added after top soil removal. Together our results point out that transplantation of later secondary succession soil can promote grassland restoration on ex-arable land

Data belonging to: Oram et al., 2020. Can flooding-induced greenhouse gas emissions be mitigated by trait-based plant species choice?

In this research project we aimed to test the mitigation of N2O emissions of grassland communities that are subjected to flooding by means of the use of different plant species and their above- and belowground plant functional traits that could counteract the emissions

Data belonging to Oram et al. Plant community flood resilience in intensively managed grasslands and the role of the plant economic spectrum.

These data belong to Oram et al. (2020) Plant community flood resilience in intensively managed grasslands and the role of the plant economic spectrum. Published in Journal of Applied Ecology